Assistant Professor Indian Institute of Technology Bombay Mumbai, Maharashtra, India
The National Clean Air Programme (NCAP) Report 2019 listed 122 cities of India as non-attainment regions for air quality. The metropolitan area of Hyderabad is the sixth most populous city in India (10.2 million in 2021), and has a network of 6 Continuous Ambient Air Quality Monitoring Stations (CAAQMS) currently operating. Air quality trends analysis is performed for the complete network using a combination of Kolmogorov-Zurbenko (KZ) filter and Multiple Linear Regression analysis. It was observed that the weather patterns have a strong influence on variations in air pollutant concentrations, with a seasonal flushing effect of the monsoons between June and September months. Meteorological detrending is conducted to quantify the seasonal forcing on the regional air quality, and isolate the effect of changing emissions. This study establishes a framework to evaluate the effect of emission control measures and determine the appropriate number and location of new monitoring stations required for the region. The meteorologically detrended PM10, PM2.5, and NO2 were observed to be decreasing at the rate of 5.8 ± 0.1 µg/m3/year, 3.903 ± 0.072 µg/m3 /year, and 0.527 ± 0.028 µg/m3 /year over the five-year period (2016 – 2021) at the Bollaram industrial area. For the monitoring station near the industrial area of Pashamylaram the PM10, PM2.5, and NO2 concentrations independent of meteorological forcing decreased at the rate of 0.858 ± 0.099 µg/m3/year, 0.875 ± 0.055 µg/m3/year, and 1.187 ± 0.087 µg/m3/year over the seven-year period (2014 – 2021). The overall results from this study indicate that the mixed effect of the action plans for air pollution control in Hyderabad, and suggests the key locations to be monitored for an improved air quality assessment.
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